I. Technical Field
The present invention pertains to telecommunications, and particularly to determining load and/or congestion on high speed packet access channels.
II. Related Art and Other Considerations
In a typical cellular radio system, mobile terminals (also known as mobile stations and mobile user equipment units (UEs)) communicate via a radio access network (RAN) to one another and/or one or more core networks. The user equipment units (UEs) can be mobile stations such as mobile telephones (“cellular” telephones) and laptops with mobile termination, and thus can be, for example, portable, pocket, hand-held, computer-included, or car-mounted mobile devices which communicate voice and/or data with radio access network.
The radio access network (RAN) covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a radio base station or (in UTRAN parlance) “NodeB” (the terms such as radio base station and NodeB being used interchangeably herein). A cell is a geographical area where radio coverage is provided by the radio base station equipment at a base station site. Each cell is identified by a unique identity, which is broadcast in the cell. The base stations communicate over the air interface (e.g., radio frequencies) with the user equipment units (UE) within range of the base stations. In the radio access network, several base stations are typically connected (e.g., by landlines or microwave) to a radio network controller (RNC). The radio network controller, also sometimes termed a base station controller (BSC), supervises and coordinates various activities of the plural base stations connected thereto. The radio network controllers are typically connected to one or more core networks.
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system, which evolved from the Global System for Mobile Communications (GSM), and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology. The radio access network of the UMTS is often referred to as the “UTRAN”.
As technologies advance, various services require higher data rates and higher capacity. Although UMTS has been designed to support multi-media wireless services, in some instances it turns out that the maximum data rate is not enough to satisfy the required quality of services.
In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks and UTRAN specifically, and investigate enhanced data rate and radio capacity. One result of the forum's work is the High Speed Downlink Packet Access (HSDPA) for the downlink, which was introduced in 3GPP WCDMA specification Release 5.
Concerning High Speed Downlink Packet Access (HSDPA) generally, see, e.g., 3GPP TS 25.435 V7.1.0 (Jun. 16, 2006), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iub Interface User Plane Protocols for Common Transport Channel Data Streams (Release 7), which discusses High Speed Downlink Packet Access (HSDPA) and which is incorporated herein by reference in its entirety. Also incorporated by reference herein as being produced by the forum and having some bearing on High Speed Downlink Packet Access (HSDPA) or concepts described herein include: 3GPP TS 25.321 V7.1.0 (Jun. 23, 2006), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Medium Access Control (MAC) protocol specification (Release 7); 3GPP TS 25.331 V7.1.0 (Jun. 23, 2006), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Radio Resource Control (RRC); Protocol Specification (Release 7); 3GPP TS 25.425 V7.1.0 (Jun. 16, 2006), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iur interface user plane protocols for Common Transport Channel data streams (Release 7); and 3GPP TS 25.433 V7.1.0 (Jun. 20, 2006), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iub interface Node B Application Part (NBAP) signaling (Release 7).
High Speed Downlink Packet Access (HSDPA) achieves higher data speeds by, e.g., shifting some of the radio resource coordination and management responsibilities to the base station (RBS) from the radio network controller (RNC). Those responsibilities include one or more of the following: shared channel transmission, higher order modulation, link adaptation, radio channel dependent scheduling, and hybrid-ARQ with soft combining. In terms of fast link adaptation, the link adaptation is done by selecting the best modulation and coding scheme based on channel quality indicator from the mobile terminal (e.g., the user equipment unit (UE)). For fast scheduling, the selection of the user is done in the Node B, which has access to the link quality information, and thus can select the optimal user. Hybrid ARQ from Node B involves having a retransmission mechanism in the base station which allows fast retransmissions and quick recovery of erroneous link adaptation decisions. As a short TTI, a two millisecond (ms) TTI is used for transmissions.
In accordance with the first of the shifted responsibilities, i.e., shared channel transmission, HSDPA multiplexes user information for transmission on the high-speed downlink shared channel (HS-DSCH) in time-multiplexed intervals (called transmission time intervals (TTI)) over the air interface to the mobile terminal. Three new physical channels are introduced with HSDPA to enable HS-DSCH transmission. The high-speed shared control channel (HS-SCCH) is a downlink control channel that informs mobile devices when HSDPA data is scheduled for them, and how they can receive and decode it. The high-speed dedicated physical control channel (HS-DPCCH) is an uplink control channel used by the mobile to report the downlink channel quality and request retransmissions. The high-speed physical downlink shared channel (HS-PDSCH) is a downlink physical channel that carries the HS-DSCH user data. Several HS-PDSCHs are assigned to a mobile for each transmission. Each HS-PDSCH has a different OVSF channelization code.
HSDPA features a high speed channel (HSC) controller at the radio base station that functions, e.g., as a high speed scheduler, by multiplexing the user information for over the entire HS-DSCH bandwidth in the transmission time intervals (TTI). The HSDPA controller is commonly referred to also as HSDPA scheduler. Since HSDPA uses code multiplexing, several users can be scheduled at the same time.
The High Speed Downlink Packet Access (HSDPA) was followed by introduction of High Speed Uplink Packet Access (HSUPA) with its Enhanced Dedicated Channel (E-DCH) in the uplink in 3GPP WCDMA specification Release 6. E-DCH is a dedicated uplink channel (from a user equipment unit (UE) to a Node-B) that has been enhanced. Enhancements include using a short transmission time interval (TTI); fast hybrid ARQ (HARQ) between mobile terminal and the Node-B (with soft combining); scheduling of the transmission rates of mobile terminals from the Node-B. In addition, E-DCH retains a majority of the features characteristic for dedicated channels in the uplink.
Thus, currently WCDMA provides high speed packet access (HSPA) through the common channel HSDPA and the Enhanced Uplink (HSUPA). In their initial phases, typical implementations of HSDPA and Enhanced UL only supported interactive/background traffic, e.g., HSDPA and EUL only allocated any resources remaining after regular (e.g., pre-HSPA) dedicated channels (DCH) had consumed the resources that the dedicated channels required. Downlink control channels for EUL are included in the HSDPA power group, i.e., not in the non-HSDPA group for which DCH belongs.
Generally for WCDMA the radio network controller performs connection admission and resource allocation and scheduling functions for an admitted connection. But with the advent of HSDPA and later with EUL, it was more expedient to let the Node-B undertake (for HSDPA and EUL) some functionalities which previously were performed by the radio network controller. Thus, the Node-B was provided with a scheduler for the HSDPA and a scheduler for EUL to perform resource allocation and scheduling for connections which respectively share in the HSPDA and EUL. Thus, at least where HSDPA and EUL are involved, there is essentially a two tier allocation and scheduling: an upper tier performed by the radio network controller for connections generally, and a lower tier performed by the Node-B for connections using the HSDPA and EUL. The lower tier allocation and scheduling as performed by the Node-B occurs in a time frame of milliseconds, whereas the upper tier allocation and scheduling as performed by the radio network controller occurs with a longer time perspective (e.g., seconds).
The allocation and scheduling of the lower tier as preformed by the Node-B initially did not significantly impact the upper tier allocation and scheduling as performed by the radio network controller. This non-impact resulted, at least in part, from the aforementioned fact that the NodeB schedulers locally adapted the traffic to use the remaining power (or noise rise) resources left over from the guaranteed bit rate (GBR) traffic (e.g., conversational and streaming traffic), the guaranteed bit rate (GBR) traffic having already been admitted by the admission control function of the radio network controller. That is, for HSDPA and EUL the non-GBR traffic uses the remaining power left over from the GBR traffic.
HSDPA and EUL are continuing to evolve. For example, 3GPP Technical Specifications have introduced some basic possibility to report up and down link power consumption of the DCH and the HSDPA with its respective Enhanced Up link. See, e.g., 3GPP TS 25.433 V7.3.0 2006-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iub interface Node B Application Part (NBAP) signaling, (Release 7), Section 8.2.9 and Section 9.1.21, which are incorporated herein by reference. Using such reports, a radio network controller (RNC) can distinguish between a situation wherein DCH has encountered a power overload situation and a situation wherein high power consumption is due to heavy HSDPA or Enhanced up link traffic. The 3GPP Technical Specifications have also introduced some basic possibility for reporting (to the radio network controller (RNC) from the radio base station) required power per priority class.
In the traditional way the 3GPP has looked at the role of the NodeB, the CRNC has been seen as the controlling node for the NodeB resources. This control is retrieved by providing CRNC with measurements on, or models of, the NodeB resources. Even before the introduction of high speed (HS) shared channels, this was already a problem, e.g., for controlling the NodeB hardware (HW) resources. The simple linear standardized model introduced by 3GPP (credit and consumption laws) cannot provide an accurate model of the available HW (both architecture dependent and NodeB algorithm dependent). Upon introduction of shared channels, it was the intention that the nodeB would allow those channels to use only the remaining resources, and therefore without strict resource control from CRNC (which would be too slow anyway). As HS becomes more and more an alternative for dedicated channels, the need for controlling the nodeB resources for both dedicated and shared channels in a central location (CRNC) becomes clearer.
A “NodeB resource model” was provided to the radio network controller in conjunction with a feature known as “Audit Response”. The Audit Response provides information about the status of the NodeB to the RNC. The Audit Response includes a static NodeB resource model to the CRNC and is only intended to be reported when NodeB informs the CRNC about a change (e.g. license or hardware failure), which results in the CRNC requesting an audit from the NodeB. The Audit Response procedure is too slow and inaccurate to provide a proper congestion detection method. Moreover, as several generations of enhanced NodeB circuit boards are being produced and the technical evolution giving different resource consumption models, the present NodeB aggregate resource model becomes increasingly inaccurate.
The current approach of CRNC modeling the nodeB resources and making decisions is not a future-proof way. As mentioned, it will be too slow, inaccurate and not allow vendors to make optimal resource control decisions.
The standard has, until now, only provided some solutions for measuring the NodeB shared channel behavior. There is a required power measurement, allowing the CRNC to balance the DL power resource between dedicated (R99) and shared channels and a provided bitrate measurement. There is no provisioning for a similar power measurement on UL shared channels (i.e. the required headroom to guarantee the GBR scheduled services on E-DCH), nor is there a proper way of monitoring the situation of the non-GBR services mapped on shared channels in UL or DL. Also, as power is not the only limiting resource, there is information missing about the type of resources nodeB requires to satisfy the users (e.g. codes, HW).
A basic problem now exists in view, e.g., of the discrepancies in time perspective between the radio network controller (RNC) and the radio base station (RBS) as these nodes perform their above-summarized responsibilities. A basic problem is that the existing RBS-to-RNC reporting is not sufficient (e.g., not fast enough and/or accurate enough) to enable good resource handling and prioritization by the radio network controller. The basic problem is illustrated by the four following example perplexing scenarios.
First Scenario: If resources are to be reserved for the interactive/background traffic on HSDPA, the existing solution is not able to report when that reservation can not be fulfilled by the radio base station. This inability occurs because the current standard does not provide complete information in the current set of measurements. Summing up the ‘required power per priority class’ and the ‘total non-HS power’ and subtracting that from the ‘total carrier power’ (Pwr_used) respective ‘maximum cell power capability’ (Pwr_avail) will result in a Pwr_non_interactive estimate. This value will not give the required information, e.g., will not advise about the unhappiness of the non-guaranteed users mapped on HSDPA. First of all Pwr_non_interactive also includes the DL EUL power. Secondly, if Pwr_used is equal to Pwr_avail and Pwr_non_interactive is less than the reserved power level, then the radio network controller (RNC) can not know if the interactive/background traffic could utilize more resources, i.e. cannot know if the interactive/background traffic has so much more data in the buffers that it would really benefit from removing DCH or guaranteed traffic. That knowledge is only available in the RBS.
Second Scenario: The HSDPA channel generally utilizes two types of resource: channelization codes and power. When channelization code may be a limitation it is possible to increase the amount of power per code to increase the rates. Or if the power is limited, increasing the number of channelization codes employed may increase the rate. However, increasing the number of channelization codes is not always possible, because (more) channelization codes may not be available. Moreover, even if it were possible to increase the number of HS-PDSCH codes, in some situations such increase would not be beneficial if there is a limitation or lack of availability of HS-SCCH codes. With the existing solution it is not possible for the RNC to distinguish these situations, it can only receive reports of the used power or the required power per priority class. The RNC does not know when it should need to increase the number of codes to be able to solve the HSDPA overload situation. In other words, the RNC does not know what causes any unhappiness.
Third Scenario: The existing solution does not contemplate that resources could be reserved for the interactive/background traffic on EUL, and therefore the existing solution provides no mechanism for reporting when that reservation can not be fulfilled by the RBS. The current standard does not provided an indication of the required uplink power needed for scheduled GBR users on the E-DCH. Extracting the difference between total_received_power and the total_nonEUL_received power will not give required information. If the total_received_power is equal to the total_nonEUL_received_power it is not possible to know if there is any interactive E-DCH scheduled traffic that could have utilized more resources, i.e., if the interactive/background traffic has more data in the buffers so it would benefit from removing DCH or guaranteed traffic. That knowledge is only available in the radio base station.
Fourth Scenario: In accordance with the existing solution the radio network controller (RNC) does not have appropriate information from the radio base station for the radio network controller (RNC) to know which service/user is suffering, e.g., which service/user cannot have its quality of service (QoS) requirements fulfilled. Therefore the radio network controller (RNC) will never be able to take an intelligent decision of balancing the load between the DCH and the E-DCH traffic. For example, it may be to no avail to remove from the system a user on DCH with low priority who is suffering unfulfilled quality of service (QoS). But if it is a high priority E-DCH user who is having QoS problem, and there also exists a lower priority DCH user, then the RNC should remove the DCH user instead.
What is need therefore, and an object of the present invention, are one or more of apparatus, methods, techniques, and/or systems for improving the resource estimation and reporting from the radio base station to the radio network controller (RNC) to enable accurate and efficient resource control for a high speed packet access channel(s).